ESTRO 2025 - Abstract Book

S243

Brachytherapy - Gynaecology

ESTRO 2025

2031

Digital Poster Feasibility of Electronic Brachytherapy in Cervical Cancer: A Dosimetric Analysis of Early Stage Patients Sergio Lozares 1,2 , Víctor González-Pérez 3 , Naiara Fuentemilla 4 , Almudena Gandía 1 , H.P. Expósito 5 , Santiago Pellejero 4 1 Medical Physics, Miguel Servet University Hospital, Zaragoza, Spain. 2 Radiology and Radiation Protection, University of Zaragoza, Zaragoza, Spain. 3 Medical Physics, IVO Foundation, Valencia, Spain. 4 Medical Physics, University Hospital of Navarra, Pamplona, Spain. 5 Applied Physics, University of Zaragoza, Zaragoza, Spain Purpose/Objective: The aim of this study was to assess the feasibility of electronic brachytherapy (eBT) for treating cervical cancer, focusing on patients in FIGO stages I and II, and comparing eBT dosimetry with traditional 192Ir-based treatments. The objective was to evaluate whether eBT provides equivalent dosimetric outcomes in a larger cohort of early stage patients, excluding stages III and IV from the analysis. Material/Methods: A retrospective analysis was conducted on 55 patients treated with 192Ir-based interstitial brachytherapy (ISBT) from two centers. The patients were divided into FIGO stages IB-IIA (16 patients) and IIB (39 patients). Treatments were planned using MRI guidance and an Utrecht-type applicator, with interstitial needles used at the discretion of the radiotherapy team. eBT dosimetry was retrospectively calculated and compared against the original 192Ir plans using parameters including D90 and D98 for the high-risk clinical target volume (HR-CTV) and D2cc, D1cc, and D0.1cc for organs at risk (bladder, rectum, and sigmoid colon). The Mann-Whitney U test was applied to assess statistical differences, with significance set at p < 0.05. Results: Of the 55 patients, 40 (72.7%) eBT treatment plans were classified as "good" or "acceptable," similar to the original study, where 79.2% of the plans met dosimetric acceptance criteria. Specifically, 100% of plans for stage IB-IIA patients were "good," while 74.4% of stage IIB plans were either "good" or "acceptable." For HR-CTV volumes below 30 cc, all plans were classified as either "good" or "acceptable." Dosimetric comparisons showed statistically significant differences between eBT and 192Ir in D98 for HR-CTV and D1cc for the bladder, but these differences did not compromise overall treatment acceptability for early stages. Conclusion: eBT is a feasible alternative to 192Ir-based ISBT for the treatment of early-stage cervical cancer, providing appropriate dosimetry in selected cases. The findings suggest that eBT can yield equivalent treatment quality, particularly in FIGO stages I and II, where complex interstitial needle use is minimized. This highlights the potential of eBT for use in settings where traditional HDR brachytherapy resources are limited.

Keywords: Electronic brachytherapy, Cervical cancer

2064

Digital Poster Validating BRIGHT for the semi-automated brachytherapy treatment planning of cervical cancer Leah R.M. Dickhoff 1 , Ellen M. Kerkhof 1 , Heloisa H. Deuzeman 1,2 , Laura A. Velema 1 , Stephanie M. de Boer 1 , Lavinia A.L. Verhagen 1 , Danique L.J. Barten 2 , Bradley R. Pieters 2,3 , Renzo J. Scholman 4 , Pedro M. Matos 4 , Anton Bouter 4 , Carien L. Creutzberg 1 , Peter A.N. Bosman 4 , Tanja Alderliesten 1 1 Radiation Oncology, Leiden University Medical Center, Leiden, Netherlands. 2 Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands. 3 Imaging and Biomarkers, Cancer Center Amsterdam, Amsterdam, Netherlands. 4 Evolutionary Intelligence, Centrum Wiskunde & Informatica, Amsterdam, Netherlands